Background: ω-5 Gliadin is known as a major allergen in wheat-dependent exercise-induced anaphylaxis. The characteristics that make ω-5 gliadin an allergen remain unclear. Methods: Mice were sensitized by means of intraperitoneal injection of gliadin fractions together with the adjuvant alum. Anaphylactic responses were assessed by measuring body temperature and voluntary physical activity. Specific IgE levels in mouse serum were evaluated by ELISA. After oral administration of proteins to mice, concentrations of administered proteins in their portal blood were also analyzed by competitive inhibition ELISA. Results: Oral administration of ω-5 gliadin evoked significant decreases in body temperature and physical activity of sensitized mice, whereas the gliadin fraction did not induce these effects at the same dose. These responses were exercise independent. ELISA analysis revealed that IgE antibodies from sensitized mice react to ω-5 gliadin with great efficacy. After oral administration of either the gliadin fraction or ω-5 gliadin, blood levels of ω-5 gliadin were much higher than those of the gliadin fraction. Conclusions: ω-5 Gliadin caused anaphylaxis in sensitized mice, whereas the gliadin fraction did not at the same dose. The anaphylactic response was exercise independent. It is likely that IgE of sensitized mice reacts strongly to ω-5 gliadin and that ω-5 gliadin is better absorbed from the gastrointestinal tract than other components of the gliadin fraction. These results indicated that ω-5 gliadin has prominent characteristics as an allergen and that exercise might be an indirect factor in anaphylaxis induction.